This application covers an improvement of my co-pending application Ser. No. 474,390, filed May 30, 1974.
A truck or other vehicle having an extensible reach mechanism is particularly useful and advantageous in the construction field, in that loads can be picked up, delivered to the construction or building site, and lifted to and placed upon scaffolding, without the necessity for special or separate handling to transfer the load from the vehicle to the scaffold platform or other work supporting structure. This type of vehicle has the further special advantage of being able to pick up a load immediately in front of the vehicle where the ground is firm, transport the load to the work site, and deliver it to an elevated scaffold platform or partially completed building and yet avoid driving onto the usually soft backfill around and outside of the building.
Various conventional constructions of extensible reach vehicles are known including a parallelogram arrangement for the members which support the forwardly extending boom, with the members pivotally connected to one another and to the vehicle frame, and a reach type loader vehicle in which a pivoted boom and load handling device is pivoted about its one end from a trolley which is actuatable longitudinally along a fixed track mounted from the vehicle. In my above co-pending application I have disclosed an improvement over such prior art in which a unique reach linkage has the capability both of relatively long forward thrust and high vertical lift without sacrificing substantially the forward thrust at the elevated positions.
A principal object of the present invention is to provide an extensible reach linkage for a lift truck or similar vehicle which has the capability of combining substantially longer forward thrust of a load handling device at a plurality of vertical lift positions with a substantially higher maximum vertical lift position for a given range of vehicle sizes without sacrificing substantially the forward thrust at any given elevated position, and which permits the vehicle to be maneuvered readily while carrying a load.
Another object is to provide an extensible reach truck in which the load supporting device will operate to maintain the load at a predetermined attitude relative to the ground both during elevation and reach operations, and which provides maximum versatility of any selected combination of elevation and forward thrust from a negative lift position below ground level to both a higher elevation and longer forward thrust than has been heretofore possible.
Another object is to provide an extremely compact, rugged, and relatively simple extended reach mechanism of the aforesaid type which has relatively good stability in all load handling positions, and which can be adapted to various types of vehicle designs without extensive modifications of the basic structure of the mechanism.